1. High arc length of chord length
General arc length is difficult to measure and size difference is larger, so according to the chord length calculation arc length and radius, to check. The difference value can be within 10cm range, if the difference value is larger please repeatedly measure and calculate.
2. Measuring method of chord Gao Xingchang
The two endpoints of the arc are straight distance to the chord length, the midpoint of the chord length to the arc line is the chord height (or: the chord length of the midpoint perpendicular chord length draws the line to the arc height) the chord length of the arc screen is high arc length